The present invention concerns a device for the drilling of submarine foundations.
Until now, this type of drilling has been completed with standard rotating tools driven from a ship or a platform by an intermediate rod string.
However, the working of hydrocarbon fields at great depths has increasingly relied on production platforms that require extremely strong anchorage points. This is the case, for example, of the so-called "taut cable" platforms.
Such anchorage points, able to support vertical or horizontal forces on the order of 1000 or 2000 tons, call for the construction in the ground, below several hundred meters of ocean water, of posts several square meters in cross-section and several tens of meters high, and consequently call for the construction of corresponding drills.
Now, very large diameter rotary drilling poses problems that are nearly impossible to solve.
Firstly, the raising of cuttings, either in direct or reverse circulation, requires extremely high supplies of water or air.
Additionally, since the torque to be transmitted to the tool for rotating it, as well as the vertical force to be applied to this tool, are very large, the rods used have large diameters, and are consequently very bulky, heavy, fragile and expensive. Additional problems arise because of the tubing of surface ground.
This invention aims to remedy these difficulties by furnishing a drilling device with a massive capacity in which the above difficulties will be resolved, and more particularly, those difficulties tied to the transfer of energy from the surface to the drilling tools.